You have correctly identified the question as a brainstorming one. Remember when the interviewer is testing for creativity, it is vastly more important to demonstrate your ability to think creatively and comprehensively than it is to have a good structure. If you had a good structure in the first question, it won't really matter here. The biggest risk is that you have a good structure and miss some of the important issues.

With the above in mind, when I was interviewing candidates, I would consider a good approach to be:

• Mention a few of the important issues that come to mind
• Observe that some of these issues can be grouped into buckets/organised into a logical structure
• Flesh out the answer and summarize/prioritize it briefly at the end

For example a good candidate might say something like:

"That's an interesting question and a number of issues come to mind such as the number of drugs in development, the types of drugs, the stage of the drugs, and regulatory issues. In fact, I think I can break this down into certain types of issues and then make a broader list under each category. Do you mind if I take a moment to structure my thoughts?"

***at this point the candidate takes a short to think and write down a few categories before continuing****

"I think one logical way of evaluating the value of BioFuture’s existing drug pipeline would be to tackle issues sequentially, based first on those issues that will affect the probability of the drugs being approved, and then analysing the issues that could affect the profitability of the drugs if they do come to market. We could then do an analysis that combines the number of drugs, their likelihood of success, and tally up the expected value

I think the main issues could be summed up like this:

1. How likely are the drugs to get to market? For each drug we might consider:

• What types of drugs are in development and what level of expertise does BioFuture have in developing these types of drugs?
• At what stage are the various drugs at?
• How promising have the drugs performed at earlier stages?
• How novel is the drug?
• What are the main risks for each drug? 
• What is historical success rate of similar drugs at similar stages of development?

2. If drugs are approved, how profitable are they likely to be? Again for each drug we could consider:

• What conditions are the drugs being developed for? And what are the characteristics of those conditions (e.g. rare or common, life threatening or cosmetic, etc.)
• What existing treatments are on the market?
• How much investment is required to bring the drug to market?
• What is the likelihood of a competitor bringing a new alternative to market?
• Are their political reasons that could affect the profitability of the various drugs?

3. How valuable does the pipeline appear to be?:

• How many drugs are in the pipeline?
• For each drug what is their likelihood of approval and expected future value?
• How dependent is this value on the success of a few potentially very profitable drugs?